Quote Originally Posted by Tuckervill View Post
IOW, it's a meaningless marketing term.
Probably true. But the lights that doctors prescribe have a demonstrated effect, and their product information should describe their spectrum so you can compare it against midday sunlight.

As far as the consumer-grade low wattage lights - I don't have an appreciable degree of SAD, but Vita-Lite bulbs made an enormous difference in my sleep patterns when I worked in an office with no windows. I'm sure the wattage was way too low to have an effect on SAD, but the difference in my sleep was (I have to say it) "night and day."